SPRAYING CAN

BOMBE A AEROSOL

English Abstract

A spraying can, in particular for paint and paint priming materials, is put
under pressure by means of a propellant, in particular a
propellant gas, enabling the paint to be sprayed when a valve is opened. In
order to distinctly increase the amount of paint sprayed per unit
of time and to produce a thicker layer of paint on the workpiece in the same
working time, the propellant generates in the spraying can a
pressure from 4.5 to 6 bars, the amount of paint expelled when spraying is
carried out without interruption amounts to 15 g to 35 g per 10
seconds, and the paint is expelled in the form of a wide jet spray.

French Abstract

L'invention concerne une bombe à aérosol, notamment pour peintures et matériaux de préparation à la mise en peinture, soumis à une pression au moyen d'un agent propulseur, notamment un gaz propulseur, afin de permettre la projection du matériau de mise en peinture lors de l'ouverture de la valve. L'invention vise à augmenter sensiblement la quantité de peinture projetée par unité de temps, en vue de permettre la production d'une épaisseur de couche supérieure pour un temps de travail inchangé. A cet effet, l'agent propulseur produit une pression de 4,5 à 6 bar dans la bombe à aérosol; la quantité de matériau de mise en peinture projetée est comprise entre 15 et 35 g, en cas de pulvérisation ininterrompue, et la projection s'effectue sous la forme d'une pulvérisation d'un jet large.

Claims

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CLAIMS:
1. A spray can containing a paint or a paint
preparation material and a propellant gas consisting of a
propane/butane mixture that generates a pressure of
4.5 to 6 bar at 20°C in the spray can, and in which the
output takes place in form of broad-stream atomization in
such a way that the output flow rate of the paints and paint
preparation materials is 15 g to 35 g per 10 seconds for
uninterrupted flow.
2. The spray can according to claim 1, characterized
therein that the pressure in the spray can is
5.0 to 5.5 bar.
3. The spray can according to claim 1 or 2,
characterized therein that the pressure in the spray can is
5.2 bar.
4. The spray can according to claim 1, characterized
therein that an additional amount of propane is added to the
propane/butane mixture sufficient to raise the pressure in
the spray can to a desired value.
5. The spray can according to claim 3 or 4,
characterized therein that the propellant gas mixture
consists of 72% propane/butane mixture having a pressure of
4.2 bar at 20°C and 28% of propane having a pressure of
9.1 bar, such that the pressure in the spray can is
approximately 5.2 bar.

6. The spray can of, Claim 1, wherein the paint
material is output at a rate of 18 to 28 g per l0 seconds
for uninterrupted flow.
7, The spray can o~ Claim 7., wherein the paint
material is output at an output rate of 20 g to 24 g per 10
seconds for uninterrupted flow.
8. The spray of Claim 1, wherein the paint material
is discharged in a broad-stream atomization form by means
of a low-pressure broad-stream nozzle.

Description

CA 02264696 1999-03-05‘I;TI ?fi%#?§T?HS ASJENVXT¥;”T‘.”5fiSLATlGUSpray CanThe invention concerns a spray can containing a paint or paintpreparation material and a propellant, in particular apropellant gas consisting of a propane/butane mixture.Spray cans of this type are known e.g. from DE 28 19 635 CZ,DE 38 08 405 C1 or DE 195 11 771 A1 for different areas ofapplication and for a variety of materials to be sprayed andhave been sold for many years by the millions, in particularin the household and do—it—yourself sector. To use paints andpaint preparation materials in spray cans, propellantsconsisting of a propane/butane mixture having a pressure ofabout 4.7 bar (at room temperature) are often used, asdescribed in DE 28 19 635 C2.In the spray can known from W0-A-91/14638, on the other hand,environmentally friendly propellant gases are to be used whichenable an economic delivery of the active substance in thespray can. In this case, hydrocarbons such as propane, butaneor isobutane or other organic compounds such as, for example,dimethyl ether are to be expressly excluded as propellantsince, when mixed with air, they form highly explosivecompounds which are considered to be pollutants.Spray cans for paints and paint preparation materials arepredominantly’ used in the do—it—yourself sector for autorepair painting. In the trades sector or in industrialproduction painting, coatings are usually applied by means ofcompressed—air, airless, air-supported airless orelectrostatic atomization (see E. Springmann, "Farbspritzen-Beschichtungstechnik heute" in the trade journal "Farben +CA 02264696 1999-03-05Lacke"). Particularly in workshop or industrial auto repairpainting, either low-pressure paint sprayers or high—pressurepaint sprayers are used thereby. High—pressure spraying isthe most common painting method. However, even if the qualityof the surface meets the desired requirements of productionpainting in the automotive industry or for repair painting,this painting method has the greatest "overspray" and achievesa degree of application effectiveness of only about 30% to50%.While compressed air atomization takes place at pressures of1.5 to 5 bar in high-pressure spraying, atomization of thepaint material in low-pressure spraying takes place atpressures in the range of 0.7 to 1.0 bar. This low-pressurespraying method requires high air volumes, which are producedwith fans, among other things. since the atomizer pressuremust be limited to 0.7 bar in certain states of the UnitedStates, and, at the same time, a degree of applicationeffectiveness of at least 65% is required, paint sprayingdevices marketed under the designation HVLP (= High Volume LowPressure) have recently been developed. Compared withconventional compressed—air atomization at 3.5 to 4 bar, low-pressure spraying has the advantage that paint mist("overspray") is avoided to a large extent, and therefore ahigh material yield as well as a significantly improved degreeof application effectiveness is achieved.Conventional spray cans are used only to a very slight extentby professional users such as auto repair shops or inindustrial production painting because of their low paintoutput rate and their very uneven paint application; instead,they are used primarily in the do—it~yourself sector.1015202530CA 02264696 2003-07-3027754-31- 3 _Therefore, the object of the present invention isto improve spray cans of the aforementioned type in such away that their paint output amount per unit time issignificantly increased, so that a substantially greaterlayer thickness is achieved during the same working time,and the paint distribution on the work piece issubstantially improved.According to the present invention, a spray cancontaining a paint or a paint preparation material and apropellant gas consisting of a propane/butane mixture thatgenerates a pressure of 4.5 to 6 bar at 20°C in the spraycan, and in which the output takes place in form of broad-stream atomization in such a way that the output flow rateof the paints and paint preparation materials is 15 g to 35g per 10 seconds for uninterrupted flow.A spray can in accordance with this solution issuitable for use in the professional sector because of itshigher output rates, particularly for use of paints andpaint preparation materials by professional car painters.As measurement results show, the degree of applicationeffectiveness of the paint spray can according to theinvention is comparable to or better than that of a modernHVLP paint spray gun. By applying the paint material in theform of broad—stream atomization, a working speed that comesclose to the working speed of a spray gun is made possible.Furthermore, the distribution of the paint particles is sofine (because of the increased pressure in combination withthe broad-stream atomization) that the distribution and thepaint status yield comparable results as when a spray gun isused. The use of broad-stream atomization is already knownfor other areas of application. Thus, in US 4,401,271, animprovement of the Newman-Green valve "3M" is describedCA 02264696 2003-07-3027754-31_ 3a ..which, however, is used for spray applications of highlyviscous products having a high solids content. This broad-stream nozzle is completelyCA 02264696 1999-03-05unsuitable for use in paint-spray cans as, a fender,e.g.cannot be uniformly painted with it.According to a preferred embodiment of the invention, thepressure in the spray can is 5.0 to 5.5 bar. The outputamount of the paint material can then advantageously be 18 gto 28 g per 10 seconds in the case of uninterrupted output.If pressure in the spray can is 5.2 bar, in a particularlyadvantageous embodiment of the invention, the paint outputamount can be increased from usually approximately 10 g per 10seconds for conventional spray cans, which have a pressure of3.5 to 3.6 bar,unit.to about 20 g to 24 g during the same timeThis is accompanied, according to the invention, by anincreased degree of application effectiveness as compared.witha conventional spray gun. This is essentially due to the factthat no compressed air is used in the spray can according tothe invention, while in spray guns, the material to be sprayedis subjected to a pneumatic pressure that produces a paintmist and furthermore causes air recoil in front of the workpiece so that the approaching paint particles are partlythrown back. This effect is referred to as "overspray".The desired pressure increase compared to conventional spraycans can, in a further embodiment of the spray can accordingto the invention, be achieved by an additional proportion ofwhichgenerates a pressure of about 4.2 bar at 20C, up to an amountpropane added. to the known propane/butane mixture,at which the pressure in the spray can reaches the desiredvalue. A pressure of about 5.2 bar can be achieved, accordingto the invention, if the propellant gas mixture consists of72% known propane/butane mixture with a pressure of 4.2 bar at20% and 28% propane with a pressure of 9.1 bar at Zdb.CA 02264696 1999-03-05By outputting the paint material in the form of broad-streamatomization, the increased paint output amount can be atomizedmore uniformly than by the conventional round spray nozzle,resulting in a homogeneous distribution of the apintparticles, following the model of the ellipsoid spray shapeproduced by a spray gun. This makes it possible to achieveoptimum distribution of the paint materials.other characteristics, advantages and applications of theinvention are evident from the following description ofexamples of the invention in comparison with the known stateof the art.Example 1:Known spray cans usually use a propane/butane mixture as thepropellant gas, in which the ratio of propane to butane rangesfrom 50:50 to 65% propane and 35% butane. In this connection,the pressure of the propane/butane propellant gas mixture isalways adjusted by the manufacturer to precisely the desiredvalue of 4.2 bar. This, together with the paint material tobe sprayed, results in a pressure of 3.5 to 3.6 bar in thespray can.Example 2:The propellant gas mixture used in the spray can according tothe invention comprises 72% of the propane/butane mixturedescribed in Example 1 with a pressure of 4.2 bar. 28% of thepropellant gas mixture is pure propane with a pressure of 9.1bar. In total, this results in a spray can pressure of 5.2bar.CA 02264696 1999-03-05This spray can pressure, which is extremely advantageous incombination with broad-stream atomization, must beindividually adjusted for each paint material. Therefore, thepaint output also depends on the paint material to be sprayedto a significant degree. The more filler the paint materialcontains, i.e., the higher the solids content of the paintmaterial to be sprayed, the higher the pressure required toachieve the desired spray amount.By coordinating the level of the spray can pressure with theoutput amount of the paint material, a degree of applicationeffectiveness is achieved that corresponds to that of a modernHVLP paint spray gun. Also, the distribution of the paintparticles by the increased pressure and the broad-streamatomization is so fine that the paint distribution and thepaint status yield comparable results as when using a spraygun, and this is achieved at comparable working speeds.Measurements of the layer thickness show that higher layerthicknesses can be achieved during the same time unit usingthe spray can according to the invention compared to sprayguns.The paint materials used were different materials such as baselacquers, clear lacquers, cover lacquers, as well as sprayputty, corrosion protection agents, plastic adhesion agents,etc.Significant advantages of the new spray technology of thespray can according to the invention, as compared with spraygun techniques, include significant material savings becausethere are no residual amounts, only a slight amount of spraymist, a high degree of application effectiveness, and norequired consideration of pot life. Also, there will be lowerCA 02264696 1999-03-05costs due to lower energy costs (air consumption), as well assubstantially lower disposal costs for paint materials. Inaddition, handling will be reduced and there will be timesavings since no setup time is required compared to spray guntechnology, and no cleaning of spray guns is necessary. Thecan also has a lower weight, and ready-to-use paint mixturescan be used so that a mixing process is no longer necessary.